CHEMISTRY COMMUNITY

Angelica Soriano 3L

Thank you so much Dr. Lavelle for the past two quarters!!

Angelica Soriano 3L

I think that there is always a reducing and oxidizing agent in a redox reaction. The reason why they didn't give the oxidizing agent is because the question stated to only give the oxidizing agent for reactions with K>1. The other reactions in the problem didn't favor products (K<1), so the question...

Angelica Soriano 3L

To add on to what the last person said before me, the catalyst isn't formed during the mechanism.

Angelica Soriano 3L

Hi! I like to handwrite all my lecture notes and then when I review, I create a Google doc and type out all the important information in my notes so I have a place where information is easily accessible to me! It makes it easier for me to retrieve information as I go over each bullet point in his ou...

Angelica Soriano 3L

Hi! Catalysts aren't consumed in a reaction. I like to think that they can be a part of a reaction, as a reactant, but will ultimately be produced again in a later step so it's like its presence remained unchanged.

Angelica Soriano 3L

Hi! So first, we know that the rate of the reaction is determined by the slowest step. The rate law of the slow step would be: k(slow) [HClO][I-]. However, HClO is an intermediate so we can't keep that for the rate law of the overall reaction. Step 1 is a fast step that's in equilibrium. We know tha...

Angelica Soriano 3L

Dorming sounds really nice right now! These days spent inside my comfort zone are making me feel like a hermit crab. I do wonder how UCLA is going to accommodate two incoming classes coming for their three-year housing guarantee. Oh man I didn't even think about that... I agree with you; I have lit...

Angelica Soriano 3L

Colin Juett 2F wrote:I quite honestly have not even thought about it yet. I'll probably end up playing Stardew Valley and mountain biking.

I love Stardew Valley omg

Angelica Soriano 3L

I can't wait to sleep in and engage in self care!!

Angelica Soriano 3L

I love boba, I think I order it at least twice a week.

Angelica Soriano 3L

Hi, so we know that this reaction is a first-order reaction so we can use the equation:
t1/2 = 0.693/k

Now, we need to input the rate constant, k, to find the half life (t1/2). Once you find the half-life, the units will be in seconds so we have to convert it to hours.

Hope this helps!

Angelica Soriano 3L

Hi, so since the reaction is zero order, we know that we can use the integrated rate law: [A]= -kt + [A0].

We can rearrange this to solve for t. t=( [A]-[A0] )/-k

Then, you would input your given values.

Hope this helps!

Angelica Soriano 3L

Honestly, I didn't do that well on the first midterm so getting a better grade on this midterm made me feel so much better!

Angelica Soriano 3L

I only watch the anime but so far, I would have to say I'm on the Paradis' side. How about you?

Angelica Soriano 3L

My favorite song at the moment is an anime opening but it's so good!!
Shogeki - Yuko Ando
https://open.spotify.com/track/5QwAdWCn ... zzNnCQbYsg

Angelica Soriano 3L

My favorite food atm are the sliders from Dave's Hot Chicken!! They're so good :3

Angelica Soriano 3L

Attack on Titan!! It's so good, has anyone watched today's episode?

Angelica Soriano 3L

After the midterm, I had to complete my group midterm for LS7A so I couldn't immediately destress. As soon as that was over though I watched some episodes of The Queen's Gambit! :D I started it last weekend but I couldn't continue because I had to study. Also, I'm going to buy a new plant tomorrow! ...

Angelica Soriano 3L

Massimo_Capozza_1G wrote:So the larger the molecule, the more complex it is and in turn the higher the enthalpy?

Yes, generally, that is the case for entropy! (assuming that "enthalpy" was a typo)

Angelica Soriano 3L

Thanks guys for your explanations! I understand now. :)

Angelica Soriano 3L

Hi, I'd just like to clear something up that I learned while doing Sapling Question #7. When I was ordering the liquid samples from most ordered to least ordered, I originally ranked the sample with the greatest molar entropy of vaporization as the least ordered. Then, I received a message saying: &...

Angelica Soriano 3L

Thank you Mrudula!! I hope you have a good and restful Valentine's day and take the day off tomorrow :)

Angelica Soriano 3L

I have a follow up question: are all free expansions isothermal (reversible or irreversible)?

Angelica Soriano 3L

Hi, we are given those values for both water and ideal gases. The fractions like "3/2R" and "5/2R" are only used for ideal gases. I think that we are only given the Cp and Cv for monoatomic ideal gases on our constants and equations sheet, but I assume that Dr. Lavelle will provi...

Angelica Soriano 3L

I'm pretty worried too because I didn't do as well as I thought I would on the first midterm. I thought I prepared sufficiently by going to UA workshop sessions once a week and doing the textbook problems. I changed up my study habits by trying to go to UA sessions, dedicating some time to practicin...

Angelica Soriano 3L

Hi! I am able to watch it. If you are trying to access video 1 and it's not working, I recommend trying to watch video 2. I hope this helps!

Angelica Soriano 3L

Hi I wanted to start a new kdrama with my friend who has never watched one before so I wanted her first one to be a really really good one. I have watched Crash Landing On You and I thought it was really good! Please help me out :) Crash Landing On You is so good!!! Did you know Hyun Bin and Son Ye...

Angelica Soriano 3L

HI guys! quick question about the hw. When we dont finish, but keep working on some questions, is the whole assingment considered late and lost points or just the unanswered questions? I think that you can still complete it late and you can get full credit. I did that once last quarter and it ended...

Angelica Soriano 3L

I definitely get how you feel. I felt like I studied super hard for this midterm. I thought I managed my time better than last quarter, studied more, and went to more UA sessions but I ended up getting a lower grade than I did on the exams last quarter. :( We got this!! I know that you will be able ...

Angelica Soriano 3L

To find q, we will use the equation q= (n) (Cv) (deltaT). To find Cv, we will use the table given to us in the question. Then, you will multiply Cv with the given number of moles (n) and the temperature change (deltaT). To find deltaU, we have to remember that at constant volume, deltaU = q. Hope th...

Angelica Soriano 3L

Reversible and irreversible expansion refer to the different types of work that a piston can do. Reversible expansion is isothermal (meaning the temperature is constant) and occurs when a gas expands or compresses with a pressure that is equal to the external pressure. It is calculated by w=-nRT(ln...

Angelica Soriano 3L

Hi! I was wondering if someone can clarify reversible and irreversible reactions because I'm having a hard time understanding the two.

Angelica Soriano 3L

For me, I like going to UA sessions because I find that they are super helpful when explaining topics I don't understand. For test prep, definitely do the textbook problems! Some of the midterm and final questions are based off the textbook problems.

Angelica Soriano 3L

Entropy is the amount of disorder in the universe. The universe tends to increase in disorder and it takes energy to decrease entropy. Hope this helps!

Angelica Soriano 3L

Also, you can go to any TA's office hours to review your exam, not just your TA.

Angelica Soriano 3L

Hello, Under the Midterm 1 tab, there are links to the discussion section you should be joining. Those may be the same links as the regular discussion section or not, I am not sure, but I would join the ones under your TA's name under the Midterm 1 tab on CCLE to be safe. Best of luck! Thank you! I...

Angelica Soriano 3L

Hi! Just making sure, do we join our TA's regular discussion zoom link for the midterm at our lecture time?

Angelica Soriano 3L

I'd love to join!!

Angelica Soriano 3L

Hi, I wanted to clarify something about the answer to this question. So the question is asking if this statement is true or false: (b) An equilibrium reaction is not affected by increasing the concentrations of products. The answer key states: "False. Equilibrium reactions are affected by the p...

Angelica Soriano 3L

Thank you guys so much!

Angelica Soriano 3L

Hi guys, I forgot where to find the answer sheet for the textbook questions. Can someone tell me where to find it?

Angelica Soriano 3L

Hi guys, I'd just like someone to clarify question #4: At a certain temperature, the given reaction has an equilibrium constant of Kp=389 . PCl3(g)+Cl2(g)↽−−⇀PCl5(g) PCl5 is placed in a sealed container at an initial pressure of 0.0270 bar . What is the total pressure at equilibrium? When I original...

Angelica Soriano 3L

I like Spirited Away

Angelica Soriano 3L

Hello! I have never taken a proctored online exam before and this is my first time taking Dr. Lavelle's class. Any insight on how they work and tips would be greatly appreciated! Thank you! Hi! So last quarter, we used our phones to join our TA's zoom discussion. We kept our cams on and showed our ...

Angelica Soriano 3L

Yes! The change in concentration is due to the change in volume, so adding inert gases wouldn't cause a shift. Although there is an increase in pressure, there is no change in volume.

Angelica Soriano 3L

Hi, so Professor Lavelle used Kc instead of Kp because he was given Kc, the moles of PCl5, and volume of the vessel (which he used to find the concentration of PCl5). I believe the question asked to find the composition of the equilibrium mixture so since he was given Kc, Professor Lavelle found the...

Angelica Soriano 3L

Adding on to my reply, a small K value (K<10^-3) would favor the reverse reaction. If Q is smaller than K, then the forward reaction is favored because at that point in time, the concentration of reactants is smaller than the concentration of reactants at equilibrium. Since Qc=[Products]/[Reactants]...

Angelica Soriano 3L

Do the Q and the K values follow the same trend/pattern when describing on whether a system will favor reactants/products? For example in the lecture, it states if K is small, then it would favor the products (shift right) since there's more reactants at equilibrium. And if Q is smaller than K, the...

Angelica Soriano 3L

Values of K in between 10^-3 and 10^3 mean that products or reactants are only slightly favored. If it is over 1, then the products are slightly favored. Meanwhile, a value of K less than 1 means that the reactants are slightly favored. If K=1 (which is rare), then neither are favored since it impli...

Angelica Soriano 3L

Last quarter I never received a physical card so I just emailed the bookstore and they emailed me back with my code!

Angelica Soriano 3L

Is the rule with 10 -3 and 10 3 for both Kc and Kp? If so, how does that work, because don't Kc and Kp often differ from each other by several magnitudes? I would say that the rule works for both Kc and Kp since the difference in magnitudes between concentration and pressure shouldn't affect the ov...

Angelica Soriano 3L

Pierce Newman 1A wrote:
Lisa Seidl 3H wrote:Last quarter he posted them for only the first unit, so I'm assuming it will be the same this quarter.

Do you know why this is the case?

I asked this question last quarter and I was told by other people that Dr. Lavelle stated it takes a lot of time to make them.

Angelica Soriano 3L

To find the concentration of [H+] or [OH-], you would use 10^-pH or 10^-pOH.

Angelica Soriano 3L

Hi, I'd just like some clarification on this problem: In each of the following salts, either the cation or the anion is a weak acid or a weak base in water. Write the chemical equation for the proton transfer reaction of this cation or anion with water: (a) NaC6H5O I went about this problem knowing ...

Angelica Soriano 3L

Yes!! I'm pretty sure Dr. Lavelle emphasized them so we should have a general idea about the bond angles for every molecular shape.

Angelica Soriano 3L

Between CO2 and H2O, the IMFs should be dipole induced-dipole and LDFs. Hydrogen bonding can only occur when a hydrogen atom is bonded to N, O, or F and is attracted to a lone pair of electrons on another N, O, or F. If we ignore the CO2, then there is hydrogen bonding between water molecules becaus...

Angelica Soriano 3L

Hi! My TA told us that we're going to join a new link (I don't know if this is the same for all TAs) that is the same link all of her discussion sections are going to use. They're then going to split all the students among two breakout rooms where the TA will proctor one room and a helper will proc...

Angelica Soriano 3L

I may be wrong, but I believe that the exact cutoff or grade breakdown depends on how (or whether) the professor curves the grades at the end of the quarter, based on how most students did, which will likely depend on the final quite a bit. ^^ This is what I've heard. I think that our final grade w...

Angelica Soriano 3L

I'm doing okay. I've been stressed with homework and finals coming up but I'm looking forward to winter break.

Angelica Soriano 3L

How does everyone feel about the class so far? I feel like it is going well, there are some points where I could've done better. Does anyone feel the same? I like this class a lot better than AP chem. However, I feel like I could've also done better at some points. Like others have said, I'm just t...

Angelica Soriano 3L

Hi! I was just wondering if the final will remain multiple choice like the midterms and has it been announced how we'll take our final? Does anyone know if it will still be during our discussion section?

Angelica Soriano 3L

Hello! So you will know if there is a dipole-dipole interaction between two molecules (of the same type) if there's a dipole moment. A dipole moment occurs within a molecule when there is a sizable electronegativity difference between two atoms, so one atom will pull the electrons more towards itsel...

Angelica Soriano 3L

I actually felt that this midterm was a lot simpler than the previous one, mostly the material is more conceptual than math based. I worry too much about calculations :( I feel the same way!! Although I was a bit confused by the wording of some of the questions, I think that this was a bit easier t...

Angelica Soriano 3L

Okay cool, I was just going to wait through the second pass and hope enough people drop so that we can find a spot :( hopefully some spots open up! Professor Lavelle just came out and said that winter enrollment in all his classes will increase! :D I linked it down below. https://lavelle.chem.ucla....

Angelica Soriano 3L

I was wondering this too :( I think we might be able to switch into the class after our second pass if someone drops the class. I saw another post asking about waitlist spots opening up in January so I hope that we'll be able to do this.

Angelica Soriano 3L

Chem 14B filled up :( My enrollment pass starts at 11 pm and I'm not really sure what to do. I think I will start LS7A but I'm unsure what to do for my third class. I'm saving LS7A for my second pass but now I'm not sure what to take because I was going to enroll in Chem 14B and LS30B.

Angelica Soriano 3L

I'm not sure but I was unable to get a spot because all of the spots have been taken, including the waitlist. Do you know if I can still get in even if it says "closed?"

Angelica Soriano 3L

I think it is because the s orbital is closer to the nucleus than the p orbital. So the electrons in the s orbital experience a greater effective nuclear charge than the electrons in the p orbital as the p orbital is further away from the nucleus and the electrons in s orbital shield some of that c...

Angelica Soriano 3L

Hi, can someone explain why "Zeffe for an electron in a p-orbital is lower than for an electron in an s-orbital in the same shell" is true?

Angelica Soriano 3L

A dipole-induced dipole is different than LDF since a dipole-induced dipole is between a polar and nonpolar molecule while an LDF is between two nonpolar molecules. LDFs are intermolecular so it will involve interactions between the same molecules (ex: cl2, h2, o2). I'm still a bit confused because...

Angelica Soriano 3L

For your first question, yes they're the same thing just with different names (synonymous with Vanderwaal's too). For your second question, yes as well. London dispersion forces are always present because of the atom's electrons; think of it as like the "minimum force" they can have. Hope...

Angelica Soriano 3L

Hi! I was just wondering if dipole-induced dipole intermolecular forces are different from London dispersion forces (and the other names it goes by). When I was in high school, my chem teacher grouped them together. Just to clarify, dipole-induced dipole IMFs are between a molecule with a permanent ...

Angelica Soriano 3L

AJForte-2C wrote:I thinks this midterm is going to be less math based, so how are you guys studying for it?

I'm studying by going over the concepts in his outlines and seeing if I am able to explain it correctly without looking at other resources.

Angelica Soriano 3L

Yes, you're correct. Intermolecular forces are forces between molecules while intramolecular forces are within molecules. An example of an intramolecular force would be a covalent bond.

Angelica Soriano 3L

From the workshop today, Michael told us that the questions are going to be shorter because they're not math-based. However, he said the midterm should be around the same length as the last midterm because it should be faster to answer these questions.

Angelica Soriano 3L

When my anxiety gets really bad, I usually do something My HS english teacher taught me. I write down everything that could go wrong with the test and everything I'm worried about right before I take the test. Writing lets me vent my worries out and I feel like that really helps!

Angelica Soriano 3L

Nane Onanyan 1H wrote:Learning the choreo for "I Cant Stop Me" by twice B)

Hi fellow Once B)

I wish I could learn the choreo to "I Can't Stop Me" but Twice's choreos are too hard.

Angelica Soriano 3L

Yes, it'll be due on Sunday midnight next week. :-)

Angelica Soriano 3L

Hi, will there be more Audio-Visual Focus topics released later during the quarter? I found these really helpful while studying and was just wondering if we will get more for other topics. Thank you Dr. Lavelle for providing these resources! :-)

Angelica Soriano 3L

I'm pretty sure n2 = 7, and with that you would get the v = R((1/n1^2) - (1/n2^2)) to be 3.29*10^15 x ((1/4)-(1/49)). Why does n2=7? Sorry, I just looked back at your post and realized you said your n2=6. I'm not sure if we have different questions, but my #14 on Sapling states: Calculate the wavel...

Angelica Soriano 3L

Racquel Fox 3L wrote:I'm pretty sure n2 = 7, and with that you would get the v = R((1/n1^2) - (1/n2^2)) to be 3.29*10^15 x ((1/4)-(1/49)).

Why does n2=7?

Angelica Soriano 3L

Hi! I had a question on question #14, which follows: Calculate the wavelength, in nanometers, of the spectral line produced when an electron in a hydrogen atom undergoes the transition from the energy level n=6 to the level n=2. I used the equation v=R[1/n1^2-1/n2^2) and plugged n1=2 and n2=6. Then,...

Angelica Soriano 3L

Also are all UA peer-learning and TA office hours happening as usual for this week or are they cancelled because it is a midterm week? All are open to assist students. I announced this in my 1am class email 6 hours ago. Hi, I'm trying to access Melody's step-up session, but it says that it needs th...

Angelica Soriano 3L

Hi, thank you for this! I joined the group me! :-)

Angelica Soriano 3L

The wavelength range would be the shortest wavelength possible (n=7 to n=1) and the longest wavelength possible (n=7 to n=6). The reason the shorter wavelength is to a lower energy level is because this energy difference is much greater, which means the frequency of light emitted is longer, therefo...

Angelica Soriano 3L

Hi! I'm having trouble approaching this problem. The electron in a hydrogen atom is excited to the n=7 shell and emits electromagnetic radiation when returning to lower energy levels. Determine the number of spectral lines that could appear when this electron returns to the lower energy levels, as w...

Angelica Soriano 3L

I'm able to go on CCLE now! It should work for you. :)

Angelica Soriano 3L

I like to listen to music, watch Netflix, and go on drives. I've been getting into crocheting and sewing though! :D

Angelica Soriano 3L

Hello, if you want to review and study concepts the peer learning and step up programs are super helpful to me. Even if you don't have any particular question, sitting in and listening to the questions of other students would help with reviewing! However, if you're looking for specific sessions tha...

Angelica Soriano 3L

Angelica Soriano 1F wrote:
Jamie2002 wrote:Having zoom on your phone should be good enough! At least that is what my TA told me

To clarify, does that mean we'll connect to zoom on our phone and then take the midterm on another device so we can open up respondus?

Never mind! I just read the other thread. Thank you.

Angelica Soriano 3L

Jamie2002 wrote:Having zoom on your phone should be good enough! At least that is what my TA told me

To clarify, does that mean we'll connect to zoom on our phone and then take the midterm on another device so we can open up respondus?

Angelica Soriano 3L

Chem_Mod wrote:I got something going for Monday. Enjoy. :-)

I really liked the song and your music taste!! I had to shazam it so I can add it to one of my playlists. Thank you for the new music. :D

Angelica Soriano 3L

I bought it but it still hasn't shipped to me and I haven't received any info on the shipping. Will our free trial be extended if it doesn't come in time before that?

Angelica Soriano 3L

This definitely does help more with my understanding, but can someone explain to me how you could calculate them as well? Like if were to have an example, would someone be able to walk me through it? I know it is a long process to type out, but I would really appreciate it! Yes of course! If you ha...

Angelica Soriano 3L

Due to the Law of Conservation of Energy, the energy of the photon (E) is equal to the difference in energy (delta E) between the electron at its excited state and ground state.

Angelica Soriano 3L

Hi, during today's lecture Dr. Lavelle states that bound electrons have lower energy than free electrons. What is the difference between bound and free electrons? Are free electrons the ones that have been excited?

Angelica Soriano 3L

I forget how you determine what the best number of sig figs to round to at the end of a question is, based on the numbers you are given. Can anyone help clarify this for me? When multiplying or dividing, look for the least amount of sig figs in the numbers given and use that amount to round off you...

Angelica Soriano 3L

The first thing I did was figure out the molecular formulas or 2butone and 3 methyl. Every like "point" or "corner" is a carbon molecule. Every carbon molecule forms 4 bonds. So we have to imagine there are hydrogen molecules attached to each carbon to fulfill these 4 bonds. So ...

Angelica Soriano 3L

I ended up with the same answer but never got 72.1 g/mol for 2 butanone and am not sure where everyone is getting that calculation? Is that just from getting the molecular formula and then determining the molar mass? I actually just googled the molar mass of butanone :') I'm not sure if we were sup...

Angelica Soriano 3L

We are given the mass of CuNo3 but we know that we need the number of moles CuNO3 to eventually find the volume. In order to convert mass to moles, you divide the given mass (6.41 g) by the molar mass of CuNO3. Once you calculate moles CuNO3, you are now able to find the volume in L. Molarity is M =...

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